1. Field of the Invention
The present invention relates to an improved wire pull back delivery system. More specifically, the invention relates to a wire pull-back implant delivery system which utilizes a pistol grip retraction handle to retract the retractable outer sheath and deploy a medical implant for a minimally invasive application, such as an endovscular stent graft, vena cava filter, self-expanding stent, balloon expandable stent, or the like.
2. Description of the Related Art
Delivery systems for deploying medical implants, such as an endovscular stent graft, vena cava filter, self-expanding stent, balloon expandable stent or the like, are a highly developed and well known field of medical technology. These medical devices have many well known uses and applications. In particular, a stent is a prosthesis which is generally tubular and which is expanded radially in a vessel or lumen to maintain its patency. Stents are widely used in body vessels, body canals, ducts or other body lumens. A self-expanding stent is a stent which expands from a compressed delivery position to its original diameter when released from the delivery device, exerting radial force on the constricted portion of the body lumen to re-establish patency. One common self-expanding stent is manufactured of Nitinol, a nickeltitanium shape memory alloy, which can be formed and annealed, deformed at a low temperature, and recalled to its original shape with heating, such as when deployed at body temperature in the body.
Wire pull-back stent delivery systems are disclosed in U.S. Pat. No. 5,360,401 and U.S. Pat. No. 5,571,135. One important factor in delivering the stent is a controlled precise retraction of the retractable outer sheath. What is needed is a wire pull-back stent delivery system which provides for a controlled and precise retraction of the retractable outer sheath and enables the physician to accurately determine proper positioning of the stent, as well as track the retraction of the outer sheath.